This invention relates to a casting apparatus useful for shaping long plate-like objects which are thin and have a large area such as curtain walls and reliefs.
According to conventional practice, molten metal heated to a predetermined temperature is poured into a molding space defined by a mold shaping member such as molding sand. This prior art practice has the following problem:
Fluidity of the molten metal poured into the molding space is prone to influences of an attaching angle and a shape of a mold, a shape of a pouring gate, viscosity, surface tension, and thermal properties of the molten metal and the mold (such as a quantity of heat retained by the molten metal, a latent heat of solidification, specific heat, and density of the molten metal, and various thermal factors relating to the cooling power of the mold.). Therefore, where the molten metal is maintained at a predetermined temperature only before pouring, as described above, the molten metal solidifies in the molding space within a very short time which results in a short extension of the material and which sets an inevitable limitation to the thinness and length of casting products. Summary of the Invention
This invention has been made in order to solve the above problem in respect of both efficiency and economy.
Therefore, a main object of this invention is to provide a casting apparatus comprising a member defining a molding space, and a conductor for electromagnetic induction heating mounted on the member at a position away from the molding space, the conductor being electrified to generate electromagnetic induction heat for a molten metal poured into the molding space.
Another object of this invention is to provide a casting apparatus comprising a mold defining a molding space, and an electromagnetic coil mounted on an insulating material surrounding the mold in a spaced away relationship.
A further object of this invention is to provide a casting apparatus comprising an electromagnetic heating coil and a molten metal propelling means both surrounding a molding space through an insulating material.
According to this invention and particularly a main embodiment thereof to be described hereinafter, when the conductor is electrified to generate lines of magnetic force, a plurality of eddy currents are generated at positions where the lines of magnetic force cross molten metal poured into the molding space, the eddy currents creating electric resistance and rapidly heating the molten metal directly to a predetermined temperature.
Therefore, the temperature of the molten metal poured into the molding space is controlled with high precision to be a predetermined temperature, thereby maximizing the flow extension of the molten metal. This permits curtain walls and other long plate-like objects which are thin and have a large area to be shaped in a reliable and satisfactory manner. Moreover, since the molten metal is heated directly according to this invention, not only the heating time is short but heat loss is small compared with the case where, for example, an electroconductive member for defining the molding space is subjected to electromagnetic induction heating and the molten metal is heated indirectly. Thus the invention produces the above-noted effect in respect of both efficiency and economy.
Other objects and advantages of this invention will be apparent from the following description.